Dispensing systems are commonly employed in a variety of different locations for dispensing a variety of different substances. For example, dispensing systems may be used in restaurants and kitchens for dispensing condiments of various kinds.
In prior systems, substances are often dispensed from "bag-in-box" containers by a diaphragm pump. In these systems, the substance to be dispensed is sealed within a deformable bag and drawn therefrom by a pump that is capable of generating a negative pressure to draw the substance from the container and a positive pressure to dispense the substance from the pump.
Whilst these diaphragm pumps are adequate for the task of dispensing substances, they suffer from a number of problems. The most notable of which is that the diaphragm pump is prone to damage caused by excessive negative or positive pressure. This excessive pressure can cause sudden movement of the diaphragm in the diaphragm pump which may cause the diaphragm to be damaged. Accordingly, the pressure employed in such a system must be carefully controlled.
These diaphragm pumps also suffer from problems with high viscosity substances and substances having particulates suspended therein. High viscosity substances can cause the diaphragm to be subjected to excessive pressure as described above. Substances with suspended particulates often cause the pump to become clogged.
In an effort to alleviate these problems, peristaltic pumps have been recently employed for dispensing systems. These peristaltic pumps, however, suffer from the problem that acidic or alkaline substances can cause a rapid degradation of flexible pipes and membranes in the pump. Furthermore, peristaltic pumps commonly generate insufficient pressure for dispensing of highly viscous substances. Peristaltic pumps are also difficult to clean and suffer from the above mentioned problem of clogging by particulates.
In addition to the above, any pump employed for the dispensation of condiments, for example, must also be hygienic and remain free from bacterial contamination.